package com.yyt.bean_copy_demo.service;

import org.apache.commons.lang3.StringUtils;

import java.util.ArrayList;
import java.util.List;

/**
 * @author yeyangtao created at 2021/4/26 14:08
 */
public class DemoService {
    public static void main(String[] args) {
        List<String> list = new ArrayList<>(10);
        for (int i = 0; i < 10; i++) {
            list.add(null);
        }
        System.out.println(list.size());
        String res = StringUtils.join(list, ",");
        System.out.println(res);

    }
}
